Short for clockwise, CW is rotation or movement of an object similar to that of the hands on a traditional clock. Beginning from the top, a circular rotation moves to the right, and from the bottom, rotation moves to the left. For instance, when inserting or tightening a screw, you would rotate the screwdriver to the right. The image shows both an example illustration of the both the clockwise and counterclockwise directions.
An easy way to remember how to adjust screws and knobs is with the popular saying "righty tighty lefty loosey."